Electrical connector plug



Nov. 23, 1965 R. A. WHALEN 3,219,962

ELECTRI CAL CONNECTOR PLUG Filed March 27, 1964 INVENTOR.

Robert A. Wholen LAZO 8 BARRY Attorneys United States Patent 3,219,962 ELECTRICAL CONNECTGR PLUG Robert A. Whalen, 9330 W. Barnard Ave, Milwaukee, Wis. Filed Mar. 27, 1964, Ser. No. 355,185 15 Claims. (Cl. 339-14.)

This invention relates to electrical connector plugs and the like which are provided with a third or ground terminal and more particularly to a new and improved three terminal electrical connector plug which can be readily converted for use in either a two or three terminal receptacle.

The increasing demand for improvements in safety measures for electrical power tools and electrical appliances has resulted in the adoption of a three terminal type plug for all such equipment. However, the conversion of outlets in the home to accommodate such plugs has been slow and will probably take many years to complete. In the interim, manufacturers have turned to convertible plugs or adaptors so that the plugs can be used in either two or three prong outlets. The cost of manufacture and the inconvenience of adaptors has resulted in their rejection by the vast majority of users. The alternative where an adaptor is not used or is rejected is to remove or break off the third terminal. A convertible type plug is believed to be a more acceptable type for public use, but the basic problem with most of the convertible type plugs presently on the market is their inability to meet the safety requirements of the electrical industry.

The primary object of the present invention is to provide an electrical connector plug with a pivotal ground terminal that is acceptable to the electrical appliance industry.

Another object of the present invention is to provide an improved electrical connector plug that is electrically and mechanically safe and can be manufactured at a cost economically competitive with conventional two prong plugs.

Another object of the present invention is to provide an improved three prong plug which has a pivotal ground terminal that is locked in an operative position.

Another object of the present invention is to provide an improved three prong plug which can be simply converted to a two prong outlet.

A further object of the present invention is to provide an improved electrical connector that has a pivotal ground terminal which is biased to an operative direction only.

A still further object of the present invention is to provide a collapsible ground terminal type electrical connector plug that can simply and easily be converted to a two terminal type plug and which automatically returns to a three terminal type plug.

These objects are accomplished by molding a ground terminal pivot member in an electric plug body which has a pair of parallely mounted electric terminals projecting from one face of the plug. The ground terminal is mounted on a pivot pin in the member in the plug and a specially designed spring is used to lock the ground terminal in the operative position and to bias it to this position. The pivot member is secured to a third or ground lead and is located so that the ground terminal can be pivoted from an operative position parallel to the electrical terminals to an inoperative position intermediate and transverse to a plane passing through the electric terminals. The ground terminal is locked in the operative position by one end of the spring which is moved so that the ground terminal can be rotated to the in operative position. When the ground terminal is so located, it is biased to the operative position by the spring.

Patented Nov. 23, 1965 An actuator can be located so that it lies in the normal position of the thumb or fingers when the plug is inserted into either a two or three opening receptacle. The actuator may be a button or lever located external to the plug or within the plug body in close proximity to the inside surface of the wall of the plug. When the actuator is squeezed, it will cause the spring to release the ground terminal so that it can be pivoted into the groove in the face of the plug. The principle of this type of three terminal plug can also be easily incorporated in an adaptor having a three prong receptacle on one side. This would be particularly advantageous to manufacturers who are presently distributing products that have wiring harnesses already attached to the equipment.

Other objects and advantages will become more readily apparent from the following detailed description when read in connection with the accompanying drawings, in which:

FIG. 1 is a top view of the plug showing the position of the electric terminals with the ground terminal shown in the operative position and the plug body shown in phantom.

FIG. 2 is a top view of the terminals with the ground terminal shown in the inoperative position.

FIG. 3 is a side View of the plug of FIG. 1.

FIG. 4 is a front view of the plug of FIG. 1.

FIG. 5 is a projected view showing the electric terminals and ground terminal without the plug.

FIG. 6 is an exploded view of the ground terminal assembly.

FIG. 7 is a view of a modified plug using a single plate for the mounting structure.

FIG. 8 is an exploded view of the ground terminal assembly for the modified plug.

Referring more particularly to the drawings, the elec trical connector plug includes a pair of electric terminals 10, 10 crimped to electric lead lines 14, 14 and a ground terminal pivot member 16 crimped to ground lead line 18. The electric terminals and ground terminal pivot member are held in the position shown in FIGS. 1, 3 and 4 and electrically non-conductive material is molded around these members to form insulating body 20 shown in outline only. The body may be molded in any number of shapes, the rectangular outline shown by way of example only. The electric terminals and pivot member are positioned in a parallel relation with the electric terminals projecting outward from the front face 25 and the end of the pivot member recessed slightly from the face of the plug.

The pivot member is formed from a channel type member having side walls 26 with the open side of the channel facing downward. An aperture 28 is provided through the side walls in the upper front portion of the channel member and a slightly curved slot 30 along the lower edge of each of the side walls. One of the side walls is extended rearward slightly to form a crimping section 27 for attachment to the ground lead.

It should be apparent that the configuration of the pivot member and its position in the plug body can be changed so long as the ground terminal can be pivoted on the pivot member. In this respect, the channel type member can be turned up or down or it can be made of a solid member having a groove therein for receiving the ground terminal. The slot 30 could be a straight slot rather than arcuate if desired. In molding the body onto the terminals, a recess 32 (shown dotted) is left in the side of the plug for inserting pivot pin 34, spring 36 and button 38. A second recess or notch 33 (shown dotted) is left in the face 25 of the plug to house the ground terminal when it is rotated therein.

The spring generally has a U shape with legs 40 and 42 being designed to project through slots 30 in the pivot member. Leg 42 may extend through both slots but in this embodiment, it is shown curved around the side wall of the pivot member. A curl or loop 45 is provided in the head of the spring to produce an outward force between the legs so that they will be biased against the ends of the slot when they are inserted therein. Leg 40 has a slide section at 41 which will slide along the end of the slot when it is pushed toward the side wall of the pivot member causing leg 40 to move back as explained below.

A ground terminal 44 of the same channel shape as the pivot member but of slightly smaller dimension is provided with apertures 46 in side walls 48. The inner end of the ground terminal is inserted through the top of notch 33 into the pivot member with the open side of the ground terminal facing upward and apertures 46 axially aligned with apertures 28. Pivot pin 34 is inserted through apertures 23 and 46 until shoulder 50 engages the side of the pivot housing. The ground terminal is then free to pivot from an operative position which is parallel to the electric terminals to an inoperative position in slot 33 between the electric terminals. A channel shaped ground terminal is shown in the drawing but a round terminal could be used and would accomplish the same result.

With the ground terminal held in the operative position, the legs at and 42 of the spring are inserted through slots 30. Leg 4t will underlie the ground terminal a spaced distance forward of the pivot pin, thereby preventing any motion from occurring in the ground terminal. The curl in the spring is designed to engage the side of the side wall where leg 42 projects through the slot. The curvature of leg 42 will tend to hold the spring in position in the slot. When force is applied to corner 54 of the spring it will pivot generally about the curl or loop because of the sliding action of section 41 on the end of slot 30 so that the end of leg 46) will move to a position below the pivot pin. The ground terminal can then be rotated about the pivot pin into the notch. The motion of the ground terminal will push leg 40 back toward leg 42 against the spring force of the curl in the spring. Referring to FIG. 4, it can be seen that leg 46 is located vertically below the pivot pin and will produce a return force on the ground terminal when it is located in the slot. If the ground terminal is released, the bias of the spring will snap it back to the operative position and leg 40 will slide forward in the slot to a position below and forward of the ground terminal pivot, locking it in position.

Force is applied to the corner 54 of the spring by means of button 38. The button is attached to the spring after it has been positioned in the slots by inserting section 54- into groove 56 in the button. The button could be mounted on the spring before. the spring is inserted into the plug. The major or larger portion 58 of the button is designed to completely fill recess 32 and to project slightly beyond the surface of the plug. When the plug is to be inserted into a two prong receptacle, the button is squeezed slightly, pushing the spring inward. Section 41 on leg 40 will slide along the end of the slot and as a result of its angular relation will move end 40 of the spring rearward until it is vertically in alignment with the pivot pin. The ground terminal can then be pivoted into slot 33. With the ground terminal completely housed in the recess, it reduces any electrical hazard. Shofider St on the pivot pin acts as a limit stop for the button so that the spring is not bent beyond its limit. The spring may be made of a single piece of nylon which has been slotted to form two legs. The legs are insertable into the slot as described above and because of the flexible nature of nylon can be squeezed to allow for the pivotal motion of the ground terminal.

In the alternate arrangement shown in FIGS. 8 and 7, the electric terminals 60 and ground terminal pivot member 62 are secured to lead lines 64 and 66 and are molded into a plug body as described above. The difference between the two plugs is in the ground terminal assembly. The pivot member is a flat plate 68 having a projection 70 for crimping the plate on lea-d line 66. An aperture 72 is provided in the front of the plate and an arcuate slot 74 in the top of the plate. A pivot pin 81 having a shoulder 83 is used to pivotally support the ground terminal. The slot has a small recess '75 at the rear for holding the spring in the locked position. The ground terminal 76 is channel shaped with one of the side walls '78 extended rearward to form a projection 80. (The ground terminal could be cylindrical with a slot in one end for mounting on member 62;.) Spring 82 is similar to spring 36 having legs 84 and 86 and a curl or loop 88. When the spring is mounted in the plate, leg 84 is seated in recess so that it overlies projection and leg 86 is clipped into the front of slot 74. Since leg 84 is spaced rearward from the pivot pin and is seated in recess 75, it will lock the ground terminal in position. To release the ground terminal, corner Si) of the spring is pushed inward so that section slides on the end of the slot to move leg 84 out of the recess and forward to a position vertically in alignment with the pivot pin. The ground terminal can then be pushed downward into the notch in the plug body. The projection on the ground terminal will squeeze leg 84 toward leg 8-6 which will then act as a return force for the ground terminal. When the ground terminal returns to the operative position, leg 84 will slide rearward to the locking position in recess '75. Button 92 is attached to corner 9%) of the spring as described above for button 38 and is actuated in the same manner.

This type of convertible three prong plug can be used in combination with a three prong adaptor. A three prong receptacle is provided on the rear face of the plug and a convertible ground terminal arrangement on the front of the plug. This type of adaptor could then be attached to permanent three prong plugs already on the marked. There are a number of other methods of locking and releasing the ground terminal that are contemplated herein. One of these would be the provision of a block having an angled groove that is reciprocally movable in the plug body. In the initial position of the block in the plug body, it would lock the ground terminal in position and on movement of the block, the groove would be brought into alignment with the ground terminal so that it can be pivoted to an inoperative position.

Although only two embodiments of the present invention have been shown and describe-d, it should be apparent that various changes and modifications can be made to the invention without departing from the scope of the appended claims.

What is claimed is:

1. A self-grounding electrical attachment plug comprising a plug body made of an electrically non-conductive material and having at least one electric contact,

a ground terminal,

pivot means in said plug body for supporting said ground terminal, said ground terminal being pivotal from an operative position to an inoperative position within the plug body,

spring means within said plug body for locking said ground terminal in the operative position and for biasing the ground terminal from the inoperative to the operative position, and

means for relieving the locking action of the spring means to allow the ground terminal to be rotated from the operative to the inoperative position.

2. A self-grounding plug according to claim 1 wherein said pivot means comprises a support member positioned within said plug body, and

a pivot pin in said support member for pivotally sup porting said ground terminal on said support mem ber.

3. A self-grounding plug according to claim 1 wherein said spring means includes a substantially U-shaped member having one leg positioned to lock the ground terminal in the operative position and being movable to release the ground terminal for movement to the inoperative position, said one leg acting on said ground terminal in said inoperative position to bias it to the operative position.

4. A self-grounding plug according to claim 3 wherein said means for relieving the locking action comprises a button secured to the U portion of the spring and being positioned for actuation by squeezing the plug body.

5. A self-grounding plug according to claim 4 wherein said button is located internal to the plug body.

6. A self-grounding plug according to claim 4 wherein said button has one portion projecting outside of said plug body.

7. An electric plug comprising a plug body,

a pair of spaced electrical contacts supported by and projecting from said body,

a ground terminal,

support means embedded within said body and adapted to pivotally support said ground terminal,

a pivot pin positioned in said support means and said ground terminal so that said ground terminal can be pivoted from an operative position to an inoperative position, and

spring means mounted in said support means for locking said ground terminal in the operative position and for biasing the ground terminal from the inoperative position to the operative position 8. An electric plug according to claim 4 wherein said support means comprises an electrically conductive plate.

9. An electric plug comprising a pair of electrical contact blades,

a support member,

a plug body holding said blades and support member in spaced relation, said plug body having a groove running between said contact blades,

a ground terminal pivotally mounted on said support member for movement into and out of said groove,

spring means in said plug body for biasing said ground terminal out of said groove and for locking said ground terminal in a fixed position relative to said blades, and

actuator means mounted on said spring means for unlocking the ground terminal so that it can be moved into said groove.

10. An electric plug according to claim 9 wherein said spring means comprises a U-shaped member having one leg positioned to engage said ground terminal and the other leg rigidly mounted in said plug body.

11. An electric plug according to claim 10 wherein said spring means includes at least one loop in the U portion of said U-shaped member.

12. An electric plug according to claim 9 wherein said support member comprises a channel shaped member embedded completely within said plug body and having a slot spaced from the pivot axis of said ground terminal, said spring means being mounted in said slot so that it engages said ground terminal a spaced distance from said pivot axis to thereby lock said ground terminal in a fixed relation with respect to said support member.

13. An electric plug according to claim 9 wherein said support member comprises a plate embedded within said plug body and having a slot spaced from the pivot axis of said ground terminal, said spring means being mounted in said slot so that it engages said ground terminal a spaced distance from said pivot axis to thereby lock said ground terminal in a fixed relation with respect to said support member.

14. An electric adaptor plug comprising a plug body having two substantially flat faces, one of said faces forming a three terminal receptacle to receive a three terminal plug, one of said terminals being connected to ground,

a pair of contact blades projecting parallely outward from said other face and being electrically connected to two of said terminal receptacles,

an electrically conductive support member connected to said ground terminal receptacle, and

a ground terminal member pivotally mounted on said support member, said plug body having a groove in said other face between said blades, said ground terminal being rotatable into said groove, and

spring means for biasing said ground terminal out of said groove and for locking said ground terminal in a fixed parallel relation with respect to said contact blades.

15. An electrical adaptor plug according to claim 14 including actuator means for unlocking said spring means from said ground terminal so that it can be pushed into said groove.

References Cited by the Examiner UNITED STATES PATENTS 2,632,789 3/1953 Modrey 3396O 2,984,808 5/1961 Bender 33914 2,986,718 5/1961 Bender 339l4 3,134,631 5/1964 Whalen 339-14 JOSEPH l SEERS, Primary Examiner, 

1. A SELF-GROUNDING ELECTRICAL ATTTACHMENT PLUG COMPRISING A PLUG BODY MADE OF AN ELECTRICALLY NON-CONDUCTIVE MATERIAL AND HAVING AT LEAST ONE ELECTRIC CONTACT, A GROUND TERMINAL, PIVOT MEANS IN SAID PLUG BODY FOR SUPPORTING SAID GROUND TERMINAL, SAID GROUND TERMINAL BEING PIVOTAL FROM AN OPERATIVE POSITION TO AN INOPERATIVE POSITION WITHIN THE PLUG BODY, SPRING MEANS WITHIN SAID PLUG BODY FOR LOCKING SAID GROUND TERMINAL IN THE OPERATIVE POSITION AND FOR BIASING THE GROUND TERMINAL FROM THE INOPERATIVE TO THE OPERATIVE POSITION, AND MEANS FOR RELIEVING THE LOCKING ACTION OF THE SPRING MEANS TO ALLOW THE GROUND THE TERMINAL TO BE ROTATED FROM THE OPERATIVE TO THE INOPERATIVE POSITION. 